Heat oven to 375°F. In large bowl, combine sugar and 1 cup margarine; beat until light and fluffy. Add sour cream and eggs; blend well. Add all remaining cookie ingredients; mix well. Drop dough by rounded tablespoonfuls onto ungreased cookie sheets.
Bake at 375°F. for 8 to 11 minutes or until edges are light golden brown. Immediately remove from cookie sheets.
Meanwhile, in small bowl, blend all frosting ingredients until smooth, adding enough orange juice for desired spreading consistency. Frost warm cookies.